Field of the Invention
Exemplary embodiments of the present invention relate to a light emitting diode (LED) illumination apparatus, and more particularly, to an LED illumination apparatus which may realize wide light distribution by increasing the angular range of radiation and achieve uniform intensity of light and a variety of light distribution patterns to reduce the loss of light that is generated by a light source and is radiated to the outside.
Discussion of the Background
Incandescent lamps and fluorescent lamps are widely used for indoor or outdoor lighting. The incandescent lamps or fluorescent lamps have a problem in that they should be frequently replaced due to their short lifespan.
In order to solve this problem, an illumination apparatus using LEDs has been developed. LEDs, when applied to illumination apparatus, have excellent characteristics, such as good controllability, rapid response, high electricity-to-light conversion efficiency, long lifetime, low power consumption, and high luminance.
In particular, the LED has an advantage in that it consumes little power due to high electricity-to-light conversion efficiency. In addition, the LED has a rapid on-off because since no preheating time is necessary, attributable to the fact that its light emission is neither thermal light emission nor discharge light emission.
Furthermore, the LED has advantages in that it is resistant to and safe from impact since neither gas nor a filament is disposed therein, in that it consumes little electrical power, operates at high repetition and high pulses, decreases optic nerve fatigue, has a lifespan so long that it can be considered semi-permanent, and realizes illumination in various colors due to the use of a stable direct lighting mode, and in that it can be miniaturized since a small light source is used.
FIG. 1 is a perspective view that illustrates a typical LED illumination apparatus. In the LED illumination apparatus, a plurality of LED devices 11 is disposed on a substrate 12, which is disposed on a heat sink 13 such that the heat that is generated when the LED devices 11 emit light can be dissipated to the outside. Heat dissipation fins 14 protrude from the outer surface of the heat sink 13 so as to increase the area of heat dissipation. A socket 15 is connected to an external power source, and a transparent cover 16 protects the LED devices 11 from the external environment.
However, since the LED device 11 defines an angular range of radiation from 120° to 130° when emitting light, an LED illumination apparatus, which is realized using the LED devices 11, exhibits a light distribution, as illustrated in FIG. 9B, which is focused substantially in the forward direction but not in the backward direction.
Accordingly, the light distribution characteristic of the LED illumination apparatus is not as good as that of an incandescent lamp, that is, light distribution in which light is directed backward, as illustrated in FIG. 9A. This causes a problem in that a sufficient intensity of illumination is not guaranteed in indoor or outdoor spaces.